(a) A colourless gas P was given off when dilute tetraoxosulphate (VI) acid was added to zinc salt Q. On bubbling the gas through lime water, a white precip...
Question 1 Report
(a) A colourless gas P was given off when dilute tetraoxosulphate (VI) acid was added to zinc salt Q. On bubbling the gas through lime water, a white precipitate R was formed. Identify P, Q and R.
(b) Name a suitable apparatus that could be used to perform each of the following activities in the laboratory
(i) storage of dilute silver trioxonitrate (V):
(ii) heating copper metal;
(iii) separation of a mixture of water and Kerosene. Give one reason for each of your answers in (b)
Answer Details
(a) The colourless gas P turns lime water milky (white precipitate R), so P is carbon(IV) oxide, CO2. A zinc salt that gives CO2 with dilute acid is a trioxocarbonate(IV), so Q is zinc trioxocarbonate(IV), ZnCO3, and R is calcium trioxocarbonate(IV), CaCO3.
\(ZnCO_3 + H_2SO_4 \rightarrow ZnSO_4 + H_2O + CO_2\); \(CO_2 + Ca(OH)_2 \rightarrow CaCO_3 + H_2O\)
(b) Suitable apparatus, with a reason for each:
- Storage of dilute silver trioxonitrate(V): a dark (amber/brown) reagent bottle, because silver trioxonitrate(V) is light-sensitive and decomposes in bright light.
- Heating copper metal: a crucible (on a pipe-clay triangle), because it can withstand strong, direct heating.
- Separating water and kerosene: a separating funnel, because the two liquids are immiscible and settle into layers that can be run off separately.
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